[arch-design-draft] Add legal content
[arch-design-draft] Add legal content

Migrate legal content from the  current guide to the draft guide

Change-Id: I38d6bf96704a0e77419f067e47eb26da7a69b308
Implements: blueprint arch-guide-mitaka-reorg

openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals